1. Field of the Invention
The invention relates to a viscous material dispensing device and more particularly to a dispensing apparatus usable in conjunction with a container of viscous material. Further, the invention relates to a method of assembling the dispensing device on a container and to a combination of a viscous material container and a dispensing device as a unit.
2. Description of the Prior Art
Removing viscous material such as shortening from a container has long been a messy operation. Often it involved the use of a tool for removing the material, a second tool for removing the material from the first tool, a second container to measure the removed material, and then another round of removal from the measuring container before the shortening could be put to use. THe extensive number of tools and steps required to get shortening from its container to a mixing bowl is not only messy, but also very time consuming and difficult to clean up. The need for a simpler manner in which to remove and measure viscous materials from containers is readily apparent, especially for viscous materials which need to be measured before using.
The prior art discloses many dispensers which can dispense and measure an amount of viscous material from a container. For example, Rich, U.S. Pat. No. 2,656,953, discloses a metered dispensing device for shortening or the like having a can with fixed top and bottom plates. A central piston is connected to the threaded post extending longitudinally through the can. The pitch of the threads on the post is gauged to cause a predetermined amount of material to be dispensed by each full turn of the cover.
Vlasich, U.S. Pat. No. 4,658,993, discloses a metering dispenser for viscous compositions wherein a piston is slidable within a chamber and is fixed to the front end of a plunger rod. The rotation of the plunger rod advances the plunger in the chamber thereby dispensing measured amounts of materials.
Strickler, U.S. Pat. No. 4,684,042, discloses a container and a pressure plate assembly which is used with a viscous material dispenser and is provided with a central threaded post. The pressure plate is forced downwardly along a threaded post to force viscous materials out of an opening at the bottom of the container.
Morel, U.S. Pat. No. 4,526,295, shows a cartridge for injecting a semi-pasty product which is provided with a central threaded rod member.
Arnold et al., U.S. Pat. No. 1,971,127, and von Schuckmann, U.S. Pat. No. 4,437,591, both disclose dispensers for pasty substances in which a piston rises on a rod in the container in response to a driving mechanism.
Most of these prior art devices comprise a piston or plate movable by a threaded shaft, and include some type of handle or drive apparatus to rotate the shaft. Although much of the prior art attempts to conveniently dispense viscous material, none have the particular combination of features which allow the user to dispense and measure a viscous material by upward motion of a piston which moves the material directly to an opening in the top of the container and allows the shaft to be rotated by a dial located on the top of the container.
One major problem not resolved by the prior art devices is the user's need of the dispensing mechanism and the material outlet opening both to be located on the top cover of the device. This is important since it allows the container to remain stationary while in use, such as at rest on a table or the like. It also allows the user to operate the device with only one hand. Prior art devices which have the dispensing mechanism and the material outlet opening on the top cover, such as Rich, U.S. Pat. No. 2,656,953, require the insertion of a tube from the container top, through the piston plate and the viscous material, to the container bottom. Thus, when the piston is pushed downwardly on the material, a portion of the material is forced up the tube and exits at the outlet opening in the top cover. This design significantly increases the number and complicity of parts, which necessarily increases manufacturing costs. Also, dispensing devices of this type are very hard to operate since the user has to force the viscous material down inside the container and then up through a relatively long tube before it can exit. Finally, when the piston of such a device is at the bottom of the container there remains a significant amount of material in the tube. This material is wasted unless removed by hand after the container has been removed, thus creating a cleanup problem.
Another problem experienced by these prior art devices is the difficulty in securing the top cover of the device to the container. Because of the forces required to push material down to the bottom of the container, then back up through the tube to an outlet opening, extraordinarily complicated and expensively manufactured means of securing the cover and container together are utilized. If not, forces intended to expel material from the container, instead cause a separation of the container from the cover. The mess, waste and inconvenience caused by a cover separating from the container while in use severely limits the device's appeal to the consumer.